Swimming on your own has its advantages and disadvantages. Some Masters swimmers have had great success by swimming on their own or with one other person from time to time. On the pro side, when swimming alone you can come and go as you please, do the sets you want to do, and not be annoyed with small talk between sets. This works for some swimmers, but ask yourself (and be honest!): how many times have you bailed on a set or interval because it was challenging? And did you bail because it was really too hard or were you just not being pushed?